Dr. Oliver Hartmanson (formerly Hartman) is the future son of Elmer Hartman. He is not born yet but according to a flashforward, he will be a 30-year-old medical doctor in the year 2070, (meaning he must have been born in 2040). He appeared in "Rich Old Stewie". He is voiced by Seth MacFarlane.
In the year 2040, Elmer Hartman and Francisco Ramirez wanted to have a baby but since they were both males, it would be impossible to have a biological one. Thankfully, due to this being the future, they used some new futuristic doctor technology in the hospital that was supposed to create human beings from human tissue. Dr. Hartman used his flesh to create a baby boy, who he named Oliver. Elmer and Francisco would raise Oliver as their son. Likewise, Francisco created a baby with his tissue too, who he named Rueben. Both of the babies ended up growing up to look exactly like their respective tissue donors, as is a natural side-effect of creating a baby with your own tissue, alone and not mixing it with someone else's.
Oliver grew up to become a doctor at the same hospital where his dad worked. In order to differentiate himself from his dad, Oliver changed his last name to "Hartmanson".
- When becoming a doctor, Oliver legally changed his last name to "Hartmanson" so that people could tell him apart from his identical father, Dr. Hartman.